Colonoscopes are used to perform a variety of surgical procedures in the colon. FIGS. 1 and 2 illustrate an embodiment of a conventional colonoscope. It has a handle (4) from which extends a flexible shaft (1), which is inserted into a hollow organ to be inspected. The shaft (1) consists of a proximal section (10), insertion tube (6), bending section (12) and a stiff section (13). The shaft terminates in the distal end (14), which typically houses main image lens (20), main illumination bulb (21), air/water nozzle (23) and the main instrument channel outlet (22). The main illumination bulb (21) is connected to a power source by an electric cable (26). The main illumination bulb (21) illuminates the area under the field of view of the main image lens (20). The main image lens (20) captures images of the illuminated area. The image is then transmitted through a fiber optic cable (27) and viewed through an eyepiece (2) on the handle (4) of the colonoscope. Alternatively, the image is transmitted to an image processor (not shown) by an electrical cable (27). The image is then processed and displayed on a display unit like a computer monitor. The handle (4) of the colonoscope has an extension arm (8) that attaches the colonoscope to a power source and an image processor. To enable the colonoscope to maneuver through the turns of a hollow organ, the shaft is flexible and incorporates a multitude of cables that attach the bending portion (12) with actuators (16&18). Tension is applied to these cables to move the bending portion (12) of the colonoscope in various directions. This is done by manual adjustment of actuators (16&18) on the handle (4) of the colonoscope. Typically, there are two pairs of such cables passing within the shaft, one pair for flexing the bending portion (12) in one plane and the other pair for flexing it in an orthogonal plane. It is also usual to provide two channels extending between the handle and the distal end of the shaft, a main air/water channel (25) and a main instrument channel (24). The main air/water channel (25) is used to insufflate air in a hollow organ to expand it for proper visualization. The main air/water channel (25) is connected proximally to an air/water pump (not shown) and a control switch (3); and distally to the main air/water channel outlet (23). The main image lens (20) and the main illumination bulb (21) are frequently smeared with blood, stool or other body fluids while in a hollow organ which obstructs a clear view. In such a situation, the main air/water channel (25) is used to eject water or blow air at the main image lens (20) and/or main illumination bulb (21) in order to clean them while still inside a hollow organ. The main instrument channel (24) has an inlet (7) proximally and an outlet (22) distally. It is used to pass various surgical instruments to do various surgical procedures. The main instrument channel is also connected to a suction valve (5) proximally and is also used to apply suction to remove fluids, air and other materials from within a hollow organ during examination.
Colonoscope is typically inserted into the patient either thorough a natural body orifice like anus or it is inserted through a surgical incision. It is then steered to a desired location by adjusting the bending portion (2) and manually pushing the colonoscope. After reaching the desired location, which usually is the end of the colon (cecum), the colonoscope is withdrawn. Typically it is during pullout when the inside of a hollow organ like colon is thoroughly examined. Insertion of the colonoscope into a hollow organ is a risky maneuver and is associated with significant complications like trauma, bleeding and perforation. It is generally desirable to complete the examination with a single insertion to minimize complications. The present colonoscopes have significant limitations. Many cancers and pre cancerous lesions (polyps) are frequently missed during colonoscopy (Pickhardt J et al, New England Journal of Medicine 2003; 349: 2191-2200). This has serious consequences including death, many of which can easily be prevented. There are two major reasons why significant lesions are missed during colonoscopy with a conventional colonoscope; 1) majority of the missed lesions lie on the rear side of mucosal folds (Pickhardt J et al; Annals of Internal Medicine 2004; 141: 352-360). With a conventional colonoscope, which is only forward viewing, the front of mucosal folds obstructs visualization of the rear side. Currently, rear side of a mucosal fold can only be examined by pushing the tip of the colonoscope beyond the said mucosal fold and bending it back upon itself in a ‘retro flexion’ maneuver. However, it is frequently not possible to achieve retro flexion in a narrow hollow organ like colon. Also, retro flexion maneuver compromises the forward view. With a conventional colonoscope, only one view, forward or backward, is possible at a given time. Complete examination of colon that includes both forward and rear views currently requires multiple insertions, one to obtain forward view and other to obtain backward view by retro flexion. However, intra colonic retro flexion can't be obtained frequently because colonic lumen is usually very narrow. Moreover, both retro flexion and multiple insertions, independently increase the morbidity, mortality, time and cost of colonoscopy; 2) another factor why lesions are frequently missed, is because conventional colonoscopes enable visualization of a given colonic segment only once. In best scenario, it enables visualization of a given colonic segment twice; once during insertion and once during withdrawl. However, it is to be remembered that traditionally colonic segments are not examined carefully during insertion, as the primary goal at that time is to reach the desired end point. It is only during pullout that the colonic segments are examined carefully. Prior studies have shown that multiple examination of a colonic segment leads to higher detection rate for polyps and cancer during colonoscopy, compared to single examination (Rex D K et al; Gastroenterology. 1997; 112(1): 24-28). Subsequent examination of a colonic segment detects polyps and cancers that were missed during previous examination.